1. Technical Field
The present disclosure relates generally to mobile communication devices adapted to operate for communications in two or more different types of wireless communication networks, such as wireless wide area networks (WWANs) and wireless local area networks (WWANs) (e.g. operative in accordance with IEEE 802.11), and more particularly to techniques for controlling the operation of wireless transceivers for communications in these networks, and/or permitting the switching of communications between such networks.
2. Description of the Related Art
When a mobile communication device is adapted to communicate through more than one physical radio domain, the mobile device may select one of the domains through which to communicate. This is true for mobile devices that support operability in both wireless local area networks (WWANs) and wireless wide area networks (WWANs). The WWANs may operate in accordance with IEEE 802.11 standards, and the WWANs may be cellular telecommunication networks (e.g. operating in accordance with Global System for Mobile communications “GSM”, General Packet Radio Service “GPRS”, Universal Mobile Telecommunication Systems “UMTS”, etc.).
Cell selection rules in specification documents typically govern cell selection techniques for a mobile device. See, for example, 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 45.008, “3rd Generation Partnership Project; Technical Specification Group GSM/EDGE Radio Access Network; Radio subsystem link control”; specifically clause 6.4 “Criteria for cell selection and reselection” and 6.6.2 “Path loss criteria and timings for cell reselection”; for UMTS devices, see e.g. TS 25.304, clause 5.2.
The cell selection technique for GSM specifies a number of monitored parameters, including a minimum RSSI required to access a candidate cell and a minimum amount of time the candidate cell should be the strongest in the list of monitored cells. Per the specification, a candidate cell may be selected by the mobile device for two different reasons: (1) the path loss criterion (C1) falls below zero for five (5) seconds (i.e. essentially no signal exists at the receiver), or (2) the calculated value of radio signal strength indicator (RSSI) criterion (C2) is greater than the C2 of serving cell for more than five (5) seconds.
If the mobile device is adapted to operate with multiple radio access technologies (RAT), the mobile device may operate to autonomously select between WLAN cells and WWAN cells. If cell selection rules similar to that outlined in the 3GPP specification were utilized for such cell selection, the mobile device might select the WLAN cell if (1) its RSSI exceeds a certain threshold level and (2) the RSSI of the candidate cell is stronger than the current serving cell for greater than some length of time (e.g. five or ten seconds). However, the WLAN transceiver of the mobile device would need to be operated or enabled often or continuously during operation with the WWAN, which would consume excessive battery power of the mobile device.
What are needed are improved methods and apparatus for controlling wireless transceiver operations for a mobile device which has multiple transceivers.